Improved ringdown waveforms in numerical relativity surrogates using domain decomposition

Gravitational inspiral-merger-ringdown (IMR) waveform modeling of binary black hole systems (BBHs) is key to our ability to detect gravitational waves and extract physics from these detections. While the most accurate scheme for the generation of these waveforms is numerical relativity, its prohibitive computational cost prevents it from being directly useful for this purpose. Numerical relativity surrogate models are powerful IMR waveform models that leverage the accuracy of numerical relativity while extending parameter space coverage, with robust, accurate models like NRSur7dq4 covering a subspace of the precessing quasi-circular parameter space. However, there is evidence to suggest that these models, while accurate over the time domain as a whole, may suffer inaccuracy within specific time subdomains, such as ringdown, which is important for performing various tests of GR and consistency checks on properties of the remnant black hole. We present a domain-decomposed methodology for surrogate construction, which we use to construct an inspiral-ringdown domain-decomposed surrogate to produce IMR waveforms of precessing quasi-circular BBHs with improved accuracy in both inspiral and ringdown.